The present invention relates generally to integrated circuits and methods of manufacturing integrated circuits. More particularly, the present invention relates to non-planar copper alloy targets for plasma vapor deposition (PVD) systems.
Semiconductor devices or integrated circuits can include millions of devices, such as, transistors. Ultra-large scale integrated (ULSI) circuits can include complementary metal oxide semiconductor (CMOS) field effect transistors (FET). Despite the ability of conventional systems and processes to fabricate millions of integrated circuit devices on an integrated circuit, there is still a need to decrease the size of integrated circuit device features, and, thus, increase the number of devices on an integrated circuit. Nevertheless, there are many factors that make the continued miniaturization of integrated circuits difficult.
One process used in the fabrication of integrated circuits is sputtering. Sputtering is a process used to deposit materials where a plasma is used to generate ions. The ions are attracted to a target, the ions impact the target and physically knock loose target atoms, and the atoms knocked loose condense out on wafers placed in the chamber depositing a film. Typically, sputtering is used to deposit metal films. Sputtering is preferred over evaporation because sputtering transfers a metal alloy from a target to a wafer with roughly the same composition on the wafer as in the target. Evaporation deposits elements at different rates depending on vapor pressure so the film on the wafer may not match the composition of the target.
A targetxe2x80x94the metal source for a sputtering processxe2x80x94is commonly round-thick pieces of metal larger in diameter than the wafers on which the metal will be deposited. In general, targets are specially shaped to optimize deposition uniformity.
Advanced plasma vapor deposition (PVD) systems require non-planar target designs to be able to induce a high ionization ratio. The non-planar shaped target also serves as a collimator, which eliminates the high angle species from the target. High angle species can be responsible for overhangs in the trench. Thus, a non-planar target can improved the conformality of sputtered film. Nevertheless, such non-planar targets can be difficult to make in copper alloy form because the mechanical properties of the alloy may cause the target to crack during the target making process. For example, a brittle Cu-alloy pallet can crack during a rolling or casting step in target making. Also, the types of alloys that can be used are limited because non-planar targets can require materials with greater workability. Further, during the deposition process, there may be particles or erosion uniformity issues that arise because of the properties of the copper alloy. Such non-uniform erosion of the target can cause alloy concentration variation within wafers.
Thus, there is a need for an improved non-planar copper alloy target for use with plasma vapor deposition systems.
Further, there is a need for a non-planar copper alloy target with improved uniform doping during the deposition process. Even further, there is a need to make a non-planar copper alloy target by forming several pieces of the target separately and fusing the pieces together.
An exemplary embodiment is related to a non-planar target configured for use in a plasma vapor deposition (PVD) process in which ions bombard the non-planar target and cause alloy atoms present in the non-planar target to be knocked loose and form an alloy film layer. The target includes a top planar section having a first alloy concentration and a side annular section having a second alloy concentration. The side annular section has an end coupled to ends of the top planar section. The first alloy concentration may not be equal to the second alloy concentration.
Another exemplary embodiment is related to a non-planar target for ion bombardment during plasma vapor deposition. The target includes two top portions having first concentrations of copper alloy atoms and side portions extending from the ends of the two top portions. Two of the side portions are coupled together by a shared footing portion at ends distal to the ends coupled to the two top portions. The side portions have second concentrations of copper alloy atoms and the first concentrations are greater than the second concentrations.
Another exemplary embodiment is related to a non-planar copper alloy target including a dome-shaped target having a first concentration of copper alloy atoms at a relatively planar top section of the dome-shaped target and a second concentration of copper alloy atoms at an annular section of the dome-shaped target. The first concentration is greater than the second concentration.
Other principle features and advantages of the invention will become apparent to those skilled in the art upon review of the following drawings, the detailed description, and the appended claims.